Four out of five college students are taking a page from Stephen Covey’s playbook, beginning with the end in mind as they pick schools they can afford and majors in high-paying disciplines. But it’s all the stuff in the middle that’s landing many in financial hot water.

About half of students blow some of their school loan money on non-educational expenses, including 3% who spent it on alcohol and drugs, according to a new Student Loan Hero survey. A handful pumped their loan money into vacations (3%); 13% ate at restaurants; 15% bought clothes; and 19% used it for car payments and other auto expenses. The greatest share (41%) spent loan funds on monthly bills, like mobile phones.

“I think they’re justifying it because of future income,” said Andrew Josuweit, CEO of Student Loan Hero. “They’re thinking, ‘This is the cost of doing business, this is my overhead.’” In other words, some students believe once they earn their degree and clinch a high-paying job, their loan payments will be chump change.

But the loan money adds up … and accrues interest. The average 2016 grad carries away $37,000 of debt along with their diploma. Students need to understand that debt can haunt them for years, said Betsy Mayotte, director of consumer outreach for American Student Assistance, a non-profit that focuses on the financing of higher education.

“If you live like a lawyer when you’re a student, you’ll live like a student when you’re a lawyer,” she said.

Beyond piling into cheaper housing with roommates or working extra hours through college, Mayotte said students should imagine their total debt in terms of monthly payments, a more concrete figure than the total sum with a row of zeros lined up like tombstones. It helps to explore free financial resources, like College Navigator, which, among other things, shows how much debt a college's graduates tend to carry.

And while 9 out of 10 students surveyed follow their passion, Mayotte said 80% of students switch majors, a potentially costly move. She recommends waiting to declare a major and exploring courses before a student decides on a focus.

"You'll have less credits you have to repeat, and less chance of additional debt," Mayotte said.